<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			/* .box1 的后代 h1标签 */
			.box1 h1{
				color: red;
			}
			
			
		</style>
	</head>
	<body>
		<div class="box1">
			<div>
				<div>
					<h1>123</h1>
				</div>
			</div>
		</div>
		<div class="box2">
			<h1>456</h1>
		</div>
	</body>
</html>